The present invention relates to a UV irradiation device.
Such a device is known from U.S. Pat. No. 5,874,740.
Microbiologically contaminated liquids, such as, for example, waste water from clarification or sewage-treatment plants, are disinfected in a particularly environmentally protective manner by being treated with ultraviolet radiation. For this purpose, various irradiation devices are known in the state of the art. With numerous applications there is a problem that the lamp units of the irradiation devices become dirty from the outside.
In the aforementioned patent a device is therefore proposed according to which annular chambers surround the lamp ends. These chambers rest against the surface of the jacket tubes where they are sealed via two O-rings. The interior of the chambers is filled via a supply unit with a cleaning liquid, for example phosphoric acid. To clean the surface of the lamp unit, the chamber that is filled with cleaning liquid is now moved back and forth on the surface, as a result of which impurities that loosely adhere are supposed to be pushed away, and deposits that strongly adhere are supposed to be dissolved by the cleaning fluid.
In practice, this device functions only to a limited extent since the O-ring seals of the chamber are very sensitive to mechanical damage or deviations in dimensions relative to the surface of the jacket tube, and furthermore the chemical action of the cleaning fluid on the surface of the jacket tube is not sufficient, without mechanical assistance, to prevent the formation of deposits, or to remove such deposits. The reaction times are too short for this purpose. For mechanically removable deposits, this device is too expensive. The O-rings themselves have no significant cleaning effect since on the one hand their circular cross section forms a very acute contact angle with the jacket tube, and on the other hand with strongly adhering or abrasive deposits the O-rings tend to roll over them.
Cleaning devices that operate entirely mechanically are also known, for example from WO 98/27011. Here a cleaning ring is moved over the surface of the jacket tube in order to remove loosely adhering impurities. Where the impurities adhere much more strongly, the effect of this cleaning device is limited.
It is therefore an object of the present invention to provide a UV irradiation device that has an effective cleaning device that operates without the supply of chemicals.